I largely agree with the thesis, but can't seem to get my head around marketing on the open Internet without being tied body and soul to the Google platform.
Today, Google Search sends the vast majority of that site's traffic and Google Adsense pays me for that traffic. I wasn't tied when I started, but I sure am now.
Mostly because they have decisively lost the search market in the United States. I deal with one of the most non-technical niches imaginable, and Google gives me 10x the traffic that Bing does. (It is an interesting question of whether this is solely because Google is crushing Bing in market share, or if it is a reflection of adaptation of my business to meet Google's demands. That is largely academic, though. Its a factor of freaking ten.
Bing and Yahoo could both go dark tomorrow permanently and I might not even notice. The last time Google went dark, for 45 minutes, I started fielding customer support queries about how I "broke the Internet". And while that is amusing phrasing, I don't think it is false. Google is navigation on the open Internet. (Insert obligatory disclaimer: for English speaking Americans. It is a bit different in Japan. It is even more lopsided in the UK in Google's favor.)
Edit to add: Do not get me started on their PPC services. Its like Bill Gates said "We want this to have the technical chops of Google and the dedication to service of a convent!" and the memo got horribly, horribly misread.